XTbe Wntverstts of Cbtcago 

FOUNDED BY JOHN D. ROCKEFELLER 



THE REFORESTATION OF SAND 

PLAINS IN VERMONT 



A DISSERTATION 

SUBMITTED TO THE FACULTY OF THE OGDEN GRADUATE SCHOOL OF 

SCIENCE IN CANDIDACY FOR THE DEGREE OF 

DOCTOR OF PHILOSOPHY 

(DEPARTMENT OF botany) 



CLIFTON DURANT HOWE 



CHICAGO 
igio 



Xlbe {University of dbtcago 

FOUNDED BY JOHN D. ROCKEFELLER 



THE REFORESTATION OF SAND 
PLAINS IN VERMONT 



A DISSERTATION 

SUBMITTED TO THE FACULTY OF THE OGDEN GRADUATE SCHOOL OF 

SCIENCE IN CANDIDACY FOR THE DEGREE OF 

DOCTOR OF PHILOSOPHY 

(DEPARTMENT OF BOTANY I 



BY 

CLIFTON DURANT HOWE 



CHICAGO 
1910 



THE REFORESTATION OF SAND PLAINS IN VERMONT 
A STUDY IN SUCCESSION 

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 1 35 

Clifton Durant Howe 

(with map and fifteen figures) 
Geology 

The region of this study is known as the Burlington-Colchester- 
Essex sand plains, which are situated at the mouth of the Winooski 
River, that flows into Lake Champlain from the Vermont side. 
The history of the plains is intimately connected with that of Lake 
Champlain. Previous to the Glacial period the present valley of the 
lake was occupied by a river 1 flowing northward. With the melting 
of the ice sheet a large lake was formed in the former river valley. 
After the Glacial period the sea invaded the region from the north, 
constituting what the older geologists called the Champlain epoch. 
At this time extensive beds of clay were laid down. The marine 
nature of these clays is demonstrated by the frequent occurrence 
of salt-water shells and by a skeleton of a whale found imbedded 
in them in the township of Charlotte. The Champlain epoch closed 
with an elevation of land which raised the marine deposits to their 
present location, the highest elevation being about ioo m above the 
present lake. With the withdrawal of the sea the valley was again 
occupied by a body of fresh water, the present Lake Champlain. 

At some time during the glacial and post-glacial history of Lake 
Champlain outlined above, bodies of water occupied three well- 
marked levels. During each of these stages a delta w r as formed by the 
erosion deposits brought down by the Winooski River. From the 
townships in which they arc located, these deltas are designated on the 
accompanying map, from oldest to youngest, as the Essex delta, the 
Colchester delta, and the Burlington-delta. The broken lines on the 
east side of each delta represent the beach lines of the lake (or sea) 
during the successive elevations. The doubling of the broken lines 

' Baldwin, S. P., Am. Geol. 13:170-184. 
Botanical Gazette, vol. 49] [126 













Map of the Burlington-Colchester-Essex Sand Plains 



128 BOTANICAL GAZETTE [February 

tree. The prevalence of old white pine stumps beneath the present 
forests, as well as the numerous white pine stump fences throughout 
the sand plains townships, contribute corroborative evidence. The 
original forest evidently contained some large trees, judged from 
present standards. Thompson (/. c.) states that he had observed trees 
52 m high, and adds that originally trees 43 to 55™ high, having a 
diameter of 2 m , were not uncommon. Stumps in various stages of 
decay which were originally at least 1.5™ in diameter may be seen 
frequently on the sand plains. 

In the clearings for settlement the commercial use of white pine 
was strictly local and very limited. Later came the period of utiliza- 
tion on a larger scale. As early as 1800^ great rafts of pine logs 
taken from the sand plains were floated down to Quebec and thence 
exported. In 1842 the historian Thompson (I.e.) asserted that the 
forests of white pine in the Champlain region had practically dis- 
appeared. In 1850 (Davis, /. c.) the importation of white pine from 
Canada began. 

The pitch pine (Finns rigida) doubtless occupied small scattered 
areas on the most sterile soils. Black oak and white oak (Qtcercus 
velutina and Q. alba) are now common on the sand plains, and they 
probably formed a minor part of both the original white pine and pitch 
pine forests. Norway pine (Pi nits resinosa) is now very local in its 
distribution on the sand plains, and it probably always was so. No 
record is to be found in regard to white birch (Bctula populifolia); 
for reasons to be discussed later it is doubtless much more abundant 
now than originally. 

Succession 

The succession on the Burlington, Colchester, and Essex sand 
plains is of two classes in respect to its place of origin, namely, upon 
cut-over areas and upon abandoned cultivated fields. 

SUCCESSION ON CUT-OVER AREAS 

As stated above, historical evidence clearly indicates that white 
pine was orginally the controlling tree on the Burlington, Colchester, 
and Essex delta plains. Only isolated trees of the original stand now 

3 Davis, W. T., The New England states 3:1524-1526. 



K)io] HOWE— REFORESTATION OF SAND PLAINS [29 

remain. The conditions following the first cutting favored the inva- 
sion of the pitch pine upon areas which it had not previously occupied. 
In the first place, having no value at that time, it was not cut, so that 
seed trees were plentiful, a thing that cannot be said of the white pine; 
in the second place, pitch pine produces seed more abundantly than 
the white pine; and finally, being more light-demanding and being 
able to endure more sterile soil conditions, it is better adapted for 
regeneration on areas cleared by lumbering. Whatever the causes 
may have been, pitch pine became the controlling tree of the second 
generation, especially on the Colchester plain. A representative list 
chart in a stand 60 years old shows 2 . 5 pitch pine on 25 s " m . Beneath 
on one square meter are 18 Myrica asplenifolia, 5 Ptcris aquilina, 
7 Kalmia angustijolia, 30 Vaccinium pennsylvanicum, 11 Vaccinium 
vacillans, 4 Carex pennsylvanica, 4 Diervilla Lonicera, 3 Solidago sp. 
(rosettes), 2 Rubus allegheniensis. 

The soil on the Burlington and Essex plains being as a whole less 
sandy, there is a larger proportion of mixed stands. On the average, 
black oak and white oak form one-third of the pitch pine stands. 
White pine of the second generation is more common on these two 
plains. 

Three brickyards and a limekiln within the sand plains furnish a 
market for pitch pine as fuel, and the pitch pine forests have been cut 
for this purpose, so that by far the greater part of the area is now in 
its second cycle of reforestation. The stands are usually cut clean of 
both trees and saplings, the latter being taken down to 5 cm in diameter. 
Sometimes a few isolated pines are left for seed trees, but they almost 
invariably die of the exposure resulting from clean cutting. The 
removal of the trees stimulated the development of the undergrowth, 
so that in most cases Myrica and Pteris became the dominant plants, 
and beneath them is a carpet of blueberries (V. pennsylvanicum and 
V. vacillans). If fire runs through, as it usually does periodically, 
the association becomes so dense as to allow no reproduction of trees. 
Often as many as 60 Myrica plants may be found on a square meter. 
The fire also keeps down the coppice shoots from the oak stumps. 
Some areas cleared 2^ years ago are still practically without tree 
reproduction. 

When the Myrica-Pteris association is 15 to 20 years old, and when 



13° 



BOTANICAL GAZETTE 



[FEBRUARY 



it has not been rejuvenated in the meantime by fire, it begins to die 
out, apparently from natural causes. The open places thus made 
give an opportunity for the reestablishment of pitch pine. The few 
lots on which this was noted show pitch pine seedlings at the rate of 



















































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Fig. i. — Sample plot 15. Cleared [5 years ago, Colchester plain, 5 meters square; 
under layer controlled by Vaccinium pennsylvanicum and Kalmia angustifolia; QA. 
Q. alba 8; A, .4ccr rubrum 5; AC, Amelanchier canadensis 2; PA, Pleris aquilina 56; 
L, Lysimachia quadrijolia 38; G, Gaultheria procumbent 14; M, Myrica asplenijolia 9; 
LC, Lvcopodiiim complanatum; Y, Polytrichum; E, Epigaea repens; ML, Melam- 
pyrum lineare 2. 



one to 5o sqm ; older stages were not found. It seems probable, how- 
ever, that eventually, if unmolested by man, such areas will regain 
their dominance of pitch pine. 

In cases where fire is kept out from the time of clearing, however, 



[<;io] 



HOWE REFORESTATION OB SAND PLAINS 



13' 



reforestation takes place more rapidly. This is brought about firsl 
by the coppice shoots of the oak and by the filling in of the intervening 
spaces by white birch (Betula populifolia), trembling aspen, red 
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FlG. 2. — Sample plot 2. Pitch pine stand, 30 years old, Colchester plain, 5 meters 
square; under layer controlled by Pteris, Gaultheria, and Vaccinium vacillans; PR, 
Finns rigida 8; QV, Q. velutina 2; QA, Q. alba 1; B, Betula populifolia 7 (dying); 
PS, Finns Strobus. 



oak coppice groups averaged three on 25 sqm , while on the lot as a 
whole, 10 per cent, of the coppice was white oak and 6 per cent, red 
maple. A dominant stand of pitch pine 24 years old was removed 
from the lot and a list chart showed on one square meter 9 Myrica, 
12 Pteris, 4 Populus tremuloides, 22 Kalmia angustijolia, 34 Vaccinium 
pennsylvanicum, 1 Rubus alleghcniensis. 



1^2 BOTANICAL GAZETTE [February 

A stand of pitch pine 45 years old with suppressed black oaks 
averaging one and three respectively per 25 s01 m , was cut clean eight 
years ago. An average square meter now supports 3 coppice groups 
of black oak, 3 Corylus americana, 1 Amelanchier canadensis, 1 Salix 
humilis; under layer, Myrica and Pteris; beneath this, Kalmia, 
Vaccinium vacittans, Lysimachia quadrijolia. The sample plot 
{■jig. 1) discloses the present conditions of a lot from which pitch pine 
was removed 15 years ago. 

When the coppice stands of oak are about 15 years old, they cover 
the area sufficiently to shade out much of the under vegetation. 
Myrica is the first to show the effects of this shading and Pteris 
goes next, while the species of Vaccinium persist longer than either 
Myrica or Pteris. V. vacittans enduring the competition with the 
trees longer than V. pennsylvanicum. At this stage the pines begin 
to reestablish themselves. Pitch pine because of its greater intoler- 
ance comes into such areas very sparsely and very slowly. ( )nly one 
place was found where it had gained control, and even there the stand 
seems destined to be displaced by the more shade-enduring white 
pine, as the sample plot {jig. 2) shows. 

For the reasons stated above, white pine is establishing itself on 
the clean-cut areas, formerly controlled by pitch pine, to a greater 
extent than the pitch pine. For example, in a lot cut 12 years ago, on 
25 sqm one finds 8 white birch saplings, 3 black oak coppice groups, 
o pitch pine seedlings, and 3 white pine seedlings; this is ioo m 
from white pine seed trees. A distance of 50'" from seed trees 
there are on 25 s ' 1 m 3 black oak coppice groups, 2 Amelanchier 
canadensis, 1 white birch, 1 red maple, 2 pitch pine seedlings, 
and 13 white pine seedlings. A still older stand is shown in sample 
plot no. 14 {fig. 3). 

The best white pine reproduction on clean-cut areas, however, is 
found where white birch controls. Thus in a clean cutting of 12 
years ago, there are now 2 white birch coppice groups, 25 birch sap- 
lings and seedlings, 6 red maple coppice groups, 20 Viburnum aceri- 
folium, 17 Corylus americana, 3 Rhus typhina, 4 Myrica, 20 Vaccinium 
vacittans, 2 white pine (8 years old); Polytrichum commune and 
Carex pennsylvanica dominant beneath. This plot is ioo m from a 
white pine seed tree. Another plot of the same size (25 sqm ) cleared 



I9I0J 



HOWE— REFORESTATION OF SAND PLAINS 



133 



15 years ago and only 5' 11 from a seed tree, shows 44 white pine seed- 
lings mostly 4 and 8 years old. The seedlings are practically all on 
little hummocks covered with Polytrichum and Mitchella. The plot 









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Fig. 3. — Sample plot 14. Cleared 20 years ago, Essex plain, 5 meters square; 
PS, Finns Strobus 14; QA, Quercus alba 8; QR, Q. rubra 7; A, Acer rubrum 6; PP, 
Prunus pennsylvanica 10; PA, Pteris aquilina 20; R, Rubus allegheniensis 15; L, 
Lysimachia quadrifolia 9; M. Myrica asplcnijolia 3; AX, Aralia nudicaulis 3; 4 V, 
Vaccinium vacillans 2; F, Fragaria sp. 1; H, Hamamelis 1. 

also contains one white pine sapling, 4 white birch and 3 black oak 
saplings, 3 Hammamelis, and 8 Corylus. 

White birch in competition with oaks and pines persists only 20 
to 30 years. Thus in a representative stand of this age one finds on 
2 5 sqm 5 white pine (5 to 14 years old), 2 black oak, 1 white oak, 3 white 
birch (nearly dead). When such stands are 35 years old the white 



134 BOTANICAL GAZETTE [February 

birch usually has disappeared, and they average on 25 sqm 2.2 white 
pine, 2.4 black oak, 0.6 white oak. Although the black oak appears 
in slightly greater numbers, the majority of them are suppressed and 
white pine dominates the stand. 

Thus it will be seen that the clean-cut areas which pass through 
the white birch stage in their reforestation end in the control of the 
white pine, and that those areas passing through the oak coppice and 
Myrica-Pteris stages are more generally succeeding to white pine 
than to pitch pine. 

SUCCESSION UPON ABANDONED CULTIVATED FIELDS 

The writer had no means of determining definitely how long the 
various fields had been cultivated before abandonment, but the 
indications are that the period was relative y short, on the average 
probably not more than 10 years. Tn some eases the fields never 
produced any other cultivated crop than rye, while in others they were 
cultivated 30 or 40 years before final abandonment. ( )ccasionally 
an old field partially reforested is cleaned off and a second attempt at 
cultivation is made. 

According to the conditions in which it takes place, the succession 
leading to the dominance of the forest upon abandoned fields may 
be discussed under the following heads: 

1. Succession lacking the preliminary herbaceous stages. This 
occurs when a plowed field near a mature stand of trees happens to 
be abandoned in a heavy seed year. 

2. Succession lacking the sod-forming stage. The herbaceous 
stages are present but the complete control of grasses i> absent or 
short-lived. 

3. Succession possessing the sod-forming stage. The natural 
course of succession here is interrupted by man, for these areas are 
cropped for grass or pastured for a longer or shorter period before 
the trees begin to take possession. 

1. Succession lacking the preliminary herbaceous stages. — 
This occurs when the abandonment of a plowed field and an abundant 
seed year are in conjunction. For example, a field on the Colchester 
plain first bore a crop of rye, then a crop of beans, and lay fallow 
the third year, when it was seeded down to white birch from the trees 



igio] 



HOWE- REFORESTATION OF SAND PLAINS 



135 



which surrounded the field. While birch seedlings two years old and 
Spiraea tomentosa now occupy the field at the rale of 53 and 4 respec- 
tively per square meter. A stand of pitch pine [6 years old showing 
63 trees on 25 sqm came into existence in the same manner. A sample 
plot in this stand is given below (fig. 4). The oaks beneath are 4 



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Fig. 4. — Sample plot 16. Pitch pine 16 years old, on abandoned plowed field, 
Colchester plain, 5 square meters; PR, Pinus rigida 63; QA, Q. alba 5; QV, Q. 
velutina 3; ML, Melampyrum linear e; M, Myrica asplenifolia c6. 

years old. Other dense even-aged stands of both white birch and 
pitch pine probably had a similar origin, although the history of their 
inception is not actually known. 

2. Succession lacking the sod-forming stage. — The character 
of the vegetation on a plowed field the first year after abandonment 
apparently depends upon the kind of weed seeds in the fertilizer. 



BOTAXICAL GAZETTE 



[FEBRUARY 



The quadrant below (fig. 5) gives the characteristic plants of a field 
which supported a crop of rye in the preceding year. Some fields may 
be controlled by Setaria glauca and Setaria viridis; others by Ambrosia 
artemisiijolia and Erigeron canadensis. Fields under observation 



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Fig. 5. — Sample plot 24. Plowed field, abandoned one year, Colchester plain, 
1 square meter; A, Ambrosia artemisiaejolia 155; PH, Plileiim pratensc 82; SN, 
Solidago nemoralis 26; P, Poa compressa 14; PC, Panicum capillare 4; R, Rumex 
Acetosella 7; J, Juncus sp. 6; E, Erigeron canadense 2; AL, .1.s7(t linariijolius \. 

for 4 years have remained under the dominance of these annuals. 
Later, Oenothera biennis, Rumex Acetosella, Gnaphalium poly- 
cephalum, Antennaria plantaginijolia, Solidago memoralis, and Aster 
linariijolius" control the old fields in patches. Between these patches 
occur scattered groups of Cyperus filiculmis, Carex pennsylvanica, 
Andropogon seoparius, and Danthonia spicata. Groups of Poly- 



igio] HOWE— REFORESTATION OB SAND PLAINS 137 

iridium appear in the most sterile places. Driving out the biennial 
and perennial weeds, the groups unite and form patches of moss a 
meter or more in diameter. The moss in turn may be crowded 
out by Cyperus and Danthonia, but it is never entirely displaced. 
Patches of Polytrichum often occupy one-third of the area in old 
fields. 

Some of the plowed fields were abandoned because they began to 
blow away, and they have since become areas of shifting sand. This 
is notably the case in several places in the townships of Colchester 
and South Burlington. The finest sand is piled up in low dunes and 
the coarser grades left behind are packed hard by the wind. Cyperus 
filiculmis and Panicum sanguinale are the pioneers on the compact 
sand; the former occurs in groups, while the latter advances en masse 
upon the sand. The open spaces between the groups of Cyperus are 
filled up by Polytrichum. 

The patches of Polytrichum in the abandoned fields described 
above form ideal germinating beds for the seeds of pitch pine, white 
pine, and white birch. This is particularly the case when the Poly- 
trichum is young, before the dead leaves and stems have accumulated 
sufficiently to prevent the seeds from reaching the mineral soil. 
Usually, however, Myrica precedes the tree invasion. It starts in the 
bed of Polytrichum and itself forms patches, killing out the moss 
immediately beneath it. The Polytrichum, however, persists around 
the margins of the Myrica group and in the moss, and under the 
protection of the Myrica one finds the tree seedlings. 

The rapidity with which trees take possession of the abandoned 
fields of this type chiefly depends upon the proximity of seed trees. 
Thus a field 370"' from seed trees, abandoned 20 years ago, has only 
41 white birch and 6 pitch pine saplings per hectare. When the pines 
get old enough to produce seed, a group of young trees will be formed 
about each mother tree. Fields showing two generations of pitch 
pine formed in this manner are of common occurrence and those 
showing three generations are not rare. The white birch, being 
shorter lived and less tolerant than the pine, is gradually suppressed, 
and the result is a pure stand of pitch pine of uneven age. A list 
chart in the field mentioned above shows on one square meter 16 
Solidago memoralis, 24 Carex pennsylvanica, 18 Lysimachia quadri- 



i38 



BOTANICAL GAZETTE 



[FEBRUARY 



folia, 8 Aster linariifolius, 6 Danthonia spicata, 2 Ambrosia artemi- 
siifolia, 1 Viola arenaria, 1 group of Andropogon scoparius. 

When the abandoned field happens to be near a mature stand of 
pitch pine, the reforestation is much more rapid. For example, an 





















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Fig. 6. — Sample plot 1 1. Pitch pine 25 years old in an old field, Colchester plain, 
5 meters square; PR, Pinus rigida 12; QV, Q. velutina 7; QA, (X alba 2; S, Spiraea 
lomenlosa 12; A, ^cer rubrum 2; B, Betula populijolia 1; M, Myrica asplenijolia 9; 
PS, Pinus Strobus. 



old field on the Colchester plain has at 270" 1 from the seed trees 
1 pitch pine and 6.3 white birch saplings on 2^' xm \ at i;o m from the 
mother stand 3 pitch pine and 1 .3 white birch; at 75 111 , 7 pitch pine 
and no white birch on 25"' m . In the second case the forest cover is 
complete and in the third case the stand is dense. At the greatest 
distance from the seed trees, the area between the birch and pine is 



1910J 



HOWE— REFOREST AT I OX OF SAND PLAINS 



J 39 



controlled by Myrica and Pteris. As the trees become more abundant 
these are gradually crowded out, until beneath the dense stand they 
disappear. The saplings nearest the seed trees are 25 years old and 
those farthest from the seed trees are 8 years old. 































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Fig. 7. — Sample plot 10. Pitch pine stand 60 years old, Colchester plain, 5 meters 
square; under layer, Carex pennsylvanica; PR, Pinus rigida 4; PS, Pinus Strobus \ 1 : 
V, Vaccinium vacillans 59; GB, Gaylussacia baccata 44; K, Kalmia angustifolia 5; 
QA, <2- tf/fo 1; L, Lysimachia quadrifolia 1 ; VP, Yacchiium pennsylvanicum 12; 
P, Pteris aquiliiia 26. 

On p. 138 is given a sample plot (/?#. (5) made in a stand of pitch 
pine 25 years old. Oaks are common in stands of this kind, but 
they are usually suppressed and apparently never become members 
of the dominant class. 

An even-aged stand of pitch pine (36 years old on the stump) 



140 



BOTANICAL GAZETTE 



FEBRTJ \KV 



on the Essex plain averages 6 trees on 25 sqm . V actinium pennsyl- 
vanicum forms a carpet beneath, and growing up through this, one 
finds on the average square meter 13 Pteris, 5 Gaylussacia baccata, 
14 Melampyrum lineare, 8 Carex pennsylvanica, 1 Rubus alleghe- 
niensis, 1 Apocynum androsaemifolium. 





























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Fig. S. — Sample pint 25. Danthonia-Folvtrichum pasture being invaded by pitch 
pine; open patches occupied by Polytrichum; Colchester plain, 1 square meter; 
D, Danthonia spicata 89; R, Riimcx Acctosella 13; F, Fra^nria virginiana 10; PC, 
Panicum capillare 6; PR, Pinits rigithi :. 

By the time pitch pine which has taken possession of the abandoned 
fields in the manner described above is 60 years old, the stand has 
become much less dense, averaging only one tree on 25 Sqm . The 
ground beneath is much less shaded and the soil is richer from the 
accumulation of humus. At this point white pine quite commonly 



igioj 



HOWE— REFORESTATION OF SAND PLAINS 



141 



reproduces itself under the protection of the pitch pine, which is 
shown in the sample plot given on p. 140 (fig. 7). 

3. Succession possessing the sod-forming stage. — Many of 
the cultivated fields on the sand plains were "seeded down," bore 
crops of hay for a few years, and then were turned over to pasturage. 


























































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Fig. 9. — Permanent sample plot 35. Forty-year-cld stand of pitch pine, Col 
Chester plain, 4 meters square; PR, Finns rigida 1; PS, Pinus Strobus 13; QV, Q. 
velutina 2; QA, Q. alba; C, Carex pennsylvanica 56; (J, Gaultheria procumbens [6; 
CU, Chimaphila umbettata 11; (ill, Gaylussacia baccata 2) 1», Diervilla Lonicera 1; 
V, V actinium vacittans 1; B, Betula populijolia 1; A, Acer ruhr urn 1; R, Rubus allc- 
gheniensis 2; S, Solidago sp. 1. 

Other helds formed a sod naturally without artificial seeding and 
were used as pastures. The chief sod-formers in this case were 
Poo pratensis and Danthonia spicata. After pastures formed in these 
two ways have been grazed for several years, they begin to lose their 
fertility. The first manifestation of this is the dying out of Poa 
pratensis, which is replaced by Danthonia. In course of time 
Danthonia gives way to Polytrichum commune. Most of the pastures 



142 



BOTAXICAL GAZETTE 



FEBRUARY 



on the area under consideration are in the Danthonia-Polytrichum 
stage. The principal associated species are Cy penis pliculmis, 
Panicum capillare, Spiraea tomentosa, Potentilla argentea, Solidago 
nemoralis, Rumex Acetosella, Aster linariifolius. 















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Fig. io. — Sample plot i. Danthonia-Polytrichum pasture, showing one-year-old 
white birch, Colchester plain, i square meter; B, Betula populijolia 40, at rate of 245 
white birch on 25 square meters; S, Spiraea tomentosa 67; PC, Poa compressa 24; 
P, Panicum capillare 21; H, Hypericum canadense 5; V, Verbena hastata 3; PT, 
Populus tremuloides 1. 



As in abandoned plowed fields, beds of Polytrichum are centers 
from which the tree invasion begins. As in the former case also, 
pitch pine and white birch are most commonly taking possession of 
worn-out pastures. Adjacent to mature pitch pine, pastures are 
transformed into pure even-aged stands of that species, while those 



1 9 1 o J 



HOWE— REFORESTATION OF SAND PLAINS 



143 



at a distance from the seed trees arc eventually covered with uneven- 
aged stands, as described for old fields in the preceding section. 
Sample plot no. 25 (fig. 8) shows the character of a pasture in the 
first stages of possession by pitch pine. 



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Fig. 11. — Sample plot 2. White birch 6 years old, pasture, Colchester plain, 
5 meters square; a carpet of Polytrichia!! commune beneath; B, Betuhi populijolia 
105; S, Spiraea tomentosa 64; O, Osmunda cinnamomea 8; M, Myrica asplenijolia 4; 
ON, Onoclea sensibilis 2; Ml', Monotropa uniflora 2; R, Rubus allegheniensis 1; 
PS, Pinus Strobus 5. 



Ten stands 5 to 15 years old averaged 34 trees on 25 sqm , while ten 
stands 25 to 30 years old averaged 7 trees. The older stands of pitch 
pine show regeneration of white pine beneath them, and plots like no. 
10 (fig. f) may be commonly found in the old pastures as well as in 
the abandoned fields. In one case white pine seedlings and saplings 



144 



BOTANICAL GAZETTE 



[FEBRUARY 



at the rate of 70 per 25 s13 m were found beneath a 24-year old stand. 
There were 7 . 5 pitch pine on 2 5 sqm . Unfortunately these stands are 
periodically burned and the seedlings are killed, so there is little 
opportunity of observing the older stages of this undergrowth of white 
pine. On the Macomber lot, however, where fire has been rigorously 



































































































































































































































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FlG. 12. — Sample plot 9. White birch [5 years old, Colchester plain, 5 meters 
square; under layer, Polytri< hum. ( hioclea sensibilis, Rubus hispidus; B, Betula populi- 
folia68; PS, Pinus Strob us [8; PT, Populus tremuloides 1; S, Spiraea tomentosa 1. 

excluded for many years, one may find the older stages. Sample plot 
35 (fig- ( ^ shows white pine 2$ years old beneath pitch pine 40 years 
old. There is little doubt of the ultimate control of such pitch pine 
stands by white pine, were forest fires excluded. 

White birch in the old pastures usually forms dense pure stands. 
The series of stands shown in figs. 10-13 illustrates displacement of 



1910] 



Ih)\YE— REFORESTATION OF SAND PLAINS 



145 



white birch by while pine. It will be noted that the numbers of white 
birch on the unit area for the ages given are 245, 105, 68, and 16; 
and that the numbers of white pine increase as follows: o, 5, 18, 46. 
This illustrates the most striking fact in the course of sueeession on 
worn-out pastures, that is, gradual replacement of white birch by 













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FIG. 13.— Sample plot 17. White birch 25 years old, 5 meters square, 50™ from 
white pine; under layer Polytrichum and Rubus hispidus; B, Betula populifolia 16; 
PS, Piwtt-s Strobus 16; QV, Quercus velutina 6; M, Myrica asplenifolia 14; S, Spiraea 

tomentosa 3; A, Acer rubnim 1. 

white pine. If a stand of white birch is within proper distance 
from white pine seed trees, the birch acts as a nurse tree to the pine. 
In the clearing of the sand plains occasional white pine trees were 
left along the margins of wood lots and along highways. Such trees 
became the originators of numerous pure stands of white pine in the 



146 



BOTAXICAL GAZETTE 



[FEBRUARY 



old pastures. Sample plot no. 37 (fig. 14) gives the character of the 
pasture when the white pine invasion begins. 

Stands of all ages occur from the seedling stage to mature trees. 
As in the case of pitch pine, one may find patches of white pine con- 



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Fig. [4.— Sample plot 37. Pasture being invaded by tin* white pine, Cblchester 
plain, 1 square meter; C, Cyperus filiculmis 72; D, Danthonia spicata 34; R, Ritmcx 
Acetosella 16; SX, Solidago nemoralis 14; H, Hypericum canadense 10; S, Spiraea 
tomentosa 6; P, Panicum capillare 4; CR, Cladonia rangifera; G, Gnaphalium poly- 
cepiialuiit 1. 

taining three generations of trees, each generation even-aged and in 
pure stand. The stands now in the process of installation offer a good 
opportunity to study the abundance of seedlings in relation to the 
distance from the mother tree. For example, the number of seedlings 
were counted on plots 5™ square with the following results: 30 to 25 111 



igio] 



HOWE— REFORESTATION OF SAND PLAINS 



147 



from the seed tree, 4 seedlings; 25 to 20 111 , 17 seedlings; 20 to 15' 1 ', 
24 seedlings; 15 to io ,n , 25 seedlings; 10 to 5™, 35 seedlings; 5-1 111 
froni a vertical line dropped from the outer margin of the crown 
of the seed tree, 85 seedlings. The seedlings were 3 and 8 years old. 





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Fig. 15. — Sample plot 13. White pine stand 35 years old, an abandoned culti- 
vated field, Essex plain, 5 meters square; PS, Pinus Strobus 14; QV, Q. velutina 2; 
QA, Q. alba 1; QR, Q. rubra 1; A, Acer rubrum 14; CA, Corylus americana 2; M, 
Maianthemum canadense 35; MR, Mitchella repens 5; Y, V actinium vacillans 1; S, 
Solidago sp. (rosette) 3. 



During their sapling stage the pure stands of white pine are usually 
so dense as to exclude secondary vegetation, but by the time they 
are 30 years old they have become thinned out sufficiently to allow 
undergrowth. This is illustrated in sample plot no. 13 (fig. 15), made 
beneath a stand 35 years old. Seedling and sapling oaks are of com- 



148 BOTANICAL GAZETTE [February 

mon occurrence beneath the older white pine in sufficient numbers to 
indicate an eventually mixed stand should they persist. 

In the discussion of succession on abandoned fields it has been 
shown that white pine is gradually regaining control of the areas on 
which it was once dominant, by the direct reseeding leading to the 
establishment of pure stands, indirectly by the supplanting of white 
birch stands, and, were human interference withdrawn, by the replace- 
ment of pitch pine stands. 

I have employed the month of vacation for the past six years in 
the study of the sand plain vegetation. Forty-five permanent sample 
plots in the stands, representing various stages of succession, have 
been established and mapped, and those have been given above which 
in my judgment best represent the conditions discussed. Most of 
these plots will be kept under observation in the future, so that definite 
records of the changes in situ may be recorded. Besides these, the 
character of the vegetation has been recorded by 100 list charts. 

While investigations have been conducted in the effort to determine 
what changes in ecological conditions have brought about the changes 
in vegetation on the sand plains, I feel that they have not progressed 
far enough to justify their publication. Therefore it seemed best to 
make the present paper simply a record of succession. The nomen- 
clature is that of Gray's New manual of bo/any. 

Summary 

Pitch pine succeeded to the control of areas from which the domi- 
nant white pine had been removed. 

White pine, however, is gradually regaining its control on cut-over 
areas, as well as on abandoned fields, by its actual replacement of 
white birch stands and by its probable displacement of the pitch pine 
stands. 

The work upon this paper was begun at the suggestion of Dr. L. R. 
Jones of the University of Vermont and was continued under Dr. 
H. C. Cowles of the University of Chicago. I wish to express my 
appreciation of the kindly criticism and encouragement received from 
them. 

University of Toronto 



i.IBRARN Or CONGRESS 



in II ii ii hi r: ill! I HUH ii s 
000 92? 573 




